TL;DR — Region Failover After AWS Outage

You operate a healthcare scheduling platform serving 5M users across the US. The primary deployment is in us-east-1 with all application servers, a PostgreSQL RDS Multi-AZ primary, Redis cluster, and S3 storage. A warm standby in us-west-2 has read replicas and a dormant application stack. DNS points to us-east-1 via Route 53 with health checks. Key features: All user-facing features must work from either region. Appointments and medical records must not be lost during failover.